Germ cells are totipotent--they can give rise to all different cell types. Ciosk et al. now show that the translational regulators MEX-3 and GLD-1 maintain totipotency in the germ line of the nematode Caenorhabditis elegans. When these two factors were eliminated, ectopic cells were found in the gonad due to the differentiation of germ cells into somatic cell types such as muscle, neurons, and intestinal cells. This transdifferentiation was associated with a loss of germ cell features such as P granules and germ cell proteins. These "worm teratomas" may be useful as a genetically tractable model system for understanding teratoma biology.